What are the neccessary that are to be satisfied to conduct Routh test?

Necessary Conditions

1.  All coefficients 1 2 1 0 a , a , a ........., a , a n n - n - should be present , ie none of them should be zero
2.  All the coefficients 1 2 1 0 a , a , a ........., a , a n n- n - should be of the same sign. If these necessary conditions (not sufficient) are satisfied, the sufficiency test can be conducted based on a Routh’s table constructed as follows.